Can't install Windows XP Pro SP3 on Dell Optiplex 790

Before you proceed further, I would suggest contacting Dell on this at this point, perhaps you can get the Dell support guys to ship you out the XP system restore disk which comes with all the relevant drivers and support for that chassis of machine.

But, if that is not what you want to do, lets proceed further with the steps you can follow.

Try to run Dell Diagnosis check to see all your Hardware is working fine, this is because we want to make sure we are clean without hardware defects.

This is down to the SATA controller driver, if you go to Dell's website and find go to the driver downloads for Optiplex 790 on XP and download the Intel driver (pre-OS) under SATA drives, copy this to a USB/floppy disk and then during the XP install press F6 when prompted.

AHCI is the recommended setting as you get better performance. Windows 7 works fine, as it has the correct drive on the install DVD, the XP being several years old does not, and causes the BSOD.

If you still cant find success. And if your hardware has no defects, you can continue with the below, its time consuming to do the below.

Here's the simplest of the hardest way to rectify the issue of loading XP SP3 on these Optiplex 790’s; it seems that the motherboard needs to be set to ATA mode in order for the system to boot.